Architectural changes to allow using JSON maps to reduce MCU serial usage

assets/qml/Components/DeviceManager.qml

@@ -66,10 +66,18 @@ Widgets.Window {
             id: commAuto
             checked: true
             text: qsTr("Auto (JSON from serial device)")
+            onCheckedChanged: {
+                if (checked)
+                    CppJsonParser.setOperationMode(CppJsonParser.kAutomatic)
+            }
         } RadioButton {
             id: commManual
             checked: false
             text: qsTr("Manual (use JSON map file)")
+            onCheckedChanged: {
+                if (checked)
+                    CppJsonParser.setOperationMode(CppJsonParser.kManual)
+            }
         }
 
         //
@@ -79,8 +87,10 @@ Widgets.Window {
             Layout.fillWidth: true
             opacity: enabled ? 1 : 0.5
             enabled: commManual.checked
-            text: qsTr("Select map file") + "..."
+            onClicked: CppJsonParser.loadJsonMap()
             Behavior on opacity {NumberAnimation{}}
+            text: CppJsonParser.jsonMapFilename.length ? qsTr("Change map file (%1)").arg(CppJsonParser.jsonMapFilename) :
+                                                         qsTr("Select map file") + "..."
         }
 
         //

src/JsonParser.cpp

@@ -23,17 +23,40 @@
 #include "JsonParser.h"
 #include "SerialManager.h"
 
+#include <QFileInfo>
+#include <QFileDialog>
+#include <QMessageBox>
+
 /*
  * Only instance of the class
  */
 static JsonParser *INSTANCE = nullptr;
 
+/**
+ * Shows a macOS-like message box with the given properties
+ */
+static int NiceMessageBox(QString text, QString informativeText, QString windowTitle = qAppName(),
+                          QMessageBox::StandardButtons buttons = QMessageBox::Ok)
+{
+   auto icon = QPixmap(":/images/icon.png").scaled(64, 64, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
+
+   QMessageBox box;
+   box.setIconPixmap(icon);
+   box.setWindowTitle(windowTitle);
+   box.setStandardButtons(buttons);
+   box.setText("<h3>" + text + "</h3>");
+   box.setInformativeText(informativeText);
+
+   return box.exec();
+}
+
 /**
  * Initializes the JSON Parser class and connects
  * appropiate SIGNALS/SLOTS
  */
 JsonParser::JsonParser()
 {
+   m_opMode = kAutomatic;
    auto sm = SerialManager::getInstance();
    connect(sm, SIGNAL(packetReceived(QByteArray)), this, SLOT(readData(QByteArray)));
 }
@@ -49,16 +72,147 @@ JsonParser *JsonParser::getInstance()
    return INSTANCE;
 }
 
+/**
+ * Returns the JSON map data from the loaded file as a string
+ */
+QByteArray JsonParser::jsonMapData() const
+{
+   return m_jsonMapData;
+}
+
 /**
  * Returns the parsed JSON document from the received packet
  */
-QJsonDocument JsonParser::document()
+QJsonDocument JsonParser::document() const
 {
    return m_document;
 }
 
 /**
- * Tries to parse the given data as a JSON document.
+ * Returns the file name (e.g. "JsonMap.json") of the loaded JSON
+ * map file
+ */
+QString JsonParser::jsonMapFilename() const
+{
+   if (m_jsonMap.isOpen())
+   {
+      auto fileInfo = QFileInfo(m_jsonMap.fileName());
+      return fileInfo.fileName();
+   }
+
+   return "";
+}
+
+/**
+ * Returns the file path of the loaded JSON map file
+ */
+QString JsonParser::jsonMapFilepath() const
+{
+   if (m_jsonMap.isOpen())
+   {
+      auto fileInfo = QFileInfo(m_jsonMap.fileName());
+      return fileInfo.filePath();
+   }
+
+   return "";
+}
+
+/**
+ * Returns the operation mode
+ */
+JsonParser::OperationMode JsonParser::operationMode() const
+{
+   return m_opMode;
+}
+
+/**
+ * Creates a file dialog & lets the user select the JSON file map
+ */
+void JsonParser::loadJsonMap()
+{
+   auto file = QFileDialog::getOpenFileName(Q_NULLPTR, tr("Select JSON map file"), QDir::homePath(),
+                                            tr("JSON files (*.json)"));
+   if (!file.isEmpty())
+      loadJsonMap(file);
+}
+
+/**
+ * Opens, validates & loads into memory the JSON file in the given @a path.
+ */
+void JsonParser::loadJsonMap(const QString &path)
+{
+   // Validate path
+   if (path.isEmpty())
+      return;
+
+   // Close previous file (if open)
+   if (m_jsonMap.isOpen())
+   {
+      m_jsonMap.close();
+      emit jsonFileMapChanged();
+   }
+
+   // Try to open the file (read only mode)
+   m_jsonMap.setFileName(path);
+   if (m_jsonMap.open(QFile::ReadOnly))
+   {
+      // Read data & validate JSON from file
+      QJsonParseError error;
+      auto data = m_jsonMap.readAll();
+      auto document = QJsonDocument::fromJson(data, &error);
+      if (error.error != QJsonParseError::NoError)
+      {
+         m_jsonMap.close();
+         NiceMessageBox(tr("JSON parse error"), error.errorString());
+      }
+
+      // JSON contains no errors
+      else
+      {
+         m_jsonMapData = data;
+         NiceMessageBox(tr("JSON map file loaded successfully!"),
+                        tr("File \"%1\" loaded into memory").arg(jsonMapFilename()));
+      }
+   }
+
+   // Open error
+   else
+   {
+      NiceMessageBox(tr("Cannot read file contents"),
+                     tr("Failed to read contents of \"%1\", check file permissions").arg(jsonMapFilename()));
+      m_jsonMap.close();
+   }
+
+   // Update UI
+   emit jsonFileMapChanged();
+}
+
+/**
+ * Changes the operation mode of the JSON parser. There are two possible op. modes:
+ *
+ * @c kManual serial data only contains the comma-separated values, and we need
+ *            to use a JSON map file (given by the user) to know what each value means.
+ *            This method is recommended when we need to transfer & display a large amount
+ *            of information from the microcontroller unit to the computer.
+ *
+ * @c kAuto serial data contains the JSON data frame, good for simple applications or
+ *          for prototyping.
+ */
+void JsonParser::setOperationMode(const OperationMode mode)
+{
+   m_opMode = mode;
+   emit operationModeChanged();
+}
+
+/**
+ * Tries to parse the given data as a JSON document according to the selected
+ * operation mode.
+ *
+ * Possible operation modes:
+ * - Auto: serial data contains the JSON data frame
+ * - Manual: serial data only contains the comma-separated values, and we need
+ *           to use a JSON map file (given by the user) to know what each value means
+ *
  * If JSON parsing is successfull, then the class shall notify the rest of the
  * application in order to process packet data.
  */

src/JsonParser.h

@@ -23,7 +23,9 @@
 #ifndef JSON_PARSER_H
 #define JSON_PARSER_H
 
+#include <QFile>
 #include <QObject>
+#include <QQmlEngine>
 #include <QJsonArray>
 #include <QJsonValue>
 #include <QJsonObject>
@@ -32,13 +34,36 @@
 class JsonParser : public QObject
 {
    Q_OBJECT
+   Q_PROPERTY(QString jsonMapFilename READ jsonMapFilename NOTIFY jsonFileMapChanged)
+   Q_PROPERTY(QString jsonMapFilepath READ jsonMapFilepath NOTIFY jsonFileMapChanged)
+   Q_PROPERTY(OperationMode operationMode READ operationMode WRITE setOperationMode NOTIFY operationModeChanged)
 
 signals:
    void packetReceived();
+   void jsonFileMapChanged();
+   void operationModeChanged();
+
+public:
+   enum OperationMode
+   {
+      kManual,
+      kAutomatic,
+   };
+   Q_ENUMS(OperationMode)
 
 public:
    static JsonParser *getInstance();
-   QJsonDocument document();
+
+   QByteArray jsonMapData() const;
+   QJsonDocument document() const;
+   QString jsonMapFilename() const;
+   QString jsonMapFilepath() const;
+   OperationMode operationMode() const;
+
+public slots:
+   void loadJsonMap();
+   void loadJsonMap(const QString &path);
+   void setOperationMode(const OperationMode mode);
 
 private:
    JsonParser();
@@ -47,7 +72,10 @@ private slots:
    void readData(const QByteArray &data);
 
 private:
+   QFile m_jsonMap;
+   OperationMode m_opMode;
    QJsonDocument m_document;
+   QByteArray m_jsonMapData;
 };
 
 #endif

src/main.cpp

@@ -34,6 +34,7 @@
 #include "AppInfo.h"
 #include "Widgets.h"
 #include "QmlBridge.h"
+#include "JsonParser.h"
 #include "GraphProvider.h"
 #include "SerialManager.h"
 
@@ -64,6 +65,7 @@ int main(int argc, char **argv)
    auto widgets = Widgets::getInstance();
    auto csvExport = Export::getInstance();
    auto qmlBridge = QmlBridge::getInstance();
+   auto jsonParser = JsonParser::getInstance();
    auto updater = QSimpleUpdater::getInstance();
    auto graphProvider = GraphProvider::getInstance();
    auto serialManager = SerialManager::getInstance();
@@ -78,6 +80,7 @@ int main(int argc, char **argv)
    engine.rootContext()->setContextProperty("CppWidgets", widgets);
    engine.rootContext()->setContextProperty("CppExport", csvExport);
    engine.rootContext()->setContextProperty("CppQmlBridge", qmlBridge);
+   engine.rootContext()->setContextProperty("CppJsonParser", jsonParser);
    engine.rootContext()->setContextProperty("CppGraphProvider", graphProvider);
    engine.rootContext()->setContextProperty("CppSerialManager", serialManager);
    engine.rootContext()->setContextProperty("CppAppName", app.applicationName());